A simple mathematical representation of Brownian motion, the Wiener equation, named after Norbert Wiener, assumes the current velocity of a fluid particle fluctuates randomly: v = d x d t = g, {\displaystyle \mathbf {v} ={\frac {d\mathbf {x} }{dt}}=g,} where v is velocity, x is position, d/dt is the time derivative, and g may for instance be white noise. Wikipedia